HYDROFORMYLATION OF 1,2-POLYBUTADIENE AND 1,4-POLYBUTADIENE AND THEIR MIXTURES WITH HYDRIDOCARBONYLTRIS(TRIPHENYLPHOSPHINE)RHODIUM(I) CATALYST AND EXCESS TRIPHENYLPHOSPHINE

The hydroformylation of 1,4-cis-poIy butadiene, 1,2-syndiotactic polybutadiene, and a mixed polybutadiene containing 12 wt % 1,2-syndiotactic and 88 wt % 1,4-cis + trans isomers using hydridocarbonyltris(triphenylphosphine)rhodium(I) homogeneous catalyst precursor with excess triphenylphosphine is examined. Through the use of13C and1H NMR spectroscopy, it is shown that hydroformylation of the 1,4-cis-polybutadiene using a PPh3/Rh molar ratio of ca. 165 at 353 K and 2066 kPa of 1:1 CO/H2 results in the exclusive formation of the internally branched aldehyde product. Hydroformylation of the 1,2-syn- diotactic polybutadiene under similar reaction conditions is shown to yield the terminal-branched aldehyde as the major product, with a trace amount of the iso-branched product. The aldehyde products obtained from the mixed polybutadiene system correspond to those obtained for the pure constituents. Comparison of kinetic data derived from gas uptake measurements shows that the initial reaction rate for hydroformylation of 1,2-syndiotactic polybutadiene is about six times greater than that obtained for hydroformylation of 1,4-cis-polybutadiene. © 1990, American Chemical Society. All rights reserved.